We did a clinical trial of succimer to treat moderately lead poisoned children. We found no effect of succimer treatment on cognition or behavior, reported previously. Recently, we have arranged with CDC to analyze blood samples collected in this project for methyl mercury, inorganic mercury, and cadmium, which allowed a randomized trial of succimer for chelation of these compounds without enrolling any new subjects or collecting any specimens. Succimer does not appear to be an efficacious chelating agent for mercury or cadmium. Neither mercury nor cadmium, measured at age 2 years, is associated with cognitive or behavioral test scores, and cadmium is not associated with blood pressure. Mercury at 7 years is associated with a small increase in the child's IQ, probably because the source of the mercury is dietary fish, and fish contains polyunsaturated fatty acids that are used in brain development. We are investigating whether we can analyze the samples for fatty acids and disentangle these effects.